How do you convert Stokes to Centistokes?

Multiply the value in Stokes by the conversion factor 100.00000000000001 to obtain the result in Centistokes.

Convert Stokes to Centistokes (St to cSt)

Reference ID: EC-KINE-STCS | EngConverter Calculation Guide

Convert From (Stokes):

Result To (Centistokes):

cSt

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In the realm of fluid mechanics and process engineering, kinematic viscosity is a fundamental physical property that describes a fluid's internal resistance to flow under the influence of gravity. The Stokes (St) is the unit of kinematic viscosity in the centimetre-gram-second (CGS) system of units, named after the Irish physicist Sir George Gabriel Stokes. While the SI unit for kinematic viscosity is square metres per second ($m^2/s$), the Stokes and its submultiple, the Centistokes (cSt), remain the dominant standards in global industry due to their convenient scaling for common liquids like water and petroleum oils.

Physical Definitions and Standards

Kinematic viscosity ($\nu$) is defined as the ratio of dynamic viscosity ($\mu$) to the density ($\rho$) of the fluid: $\nu = \mu / \rho$. One Stokes is equivalent to $1\text{ cm}^2/s$ or $10^{-4}\text{ m}^2/s$. Because the Stokes is a relatively large unit for most industrial fluids, the Centistokes ($1\text{ cSt} = 0.01\text{ St}$) is the preferred unit of measure. For reference, pure water at $20.2^\circ\text{C}$ has a kinematic viscosity of approximately $1.0\text{ cSt}$, providing a practical baseline for engineers.

Engineering Applications & Technical Considerations

In industrial process design, the conversion between Stokes and Centistokes is a daily requirement for sizing equipment and predicting flow behavior. Accurate viscosity data is critical for:

Piping and Friction Loss: The Reynolds Number ($Re = vD/\nu$), which determines whether flow is laminar or turbulent, relies directly on kinematic viscosity. Errors in unit conversion can lead to incorrect Darcy-Weisbach friction factor calculations, resulting in undersized pumps or excessive pressure drops.
Equipment Sizing: Centrifugal pump performance curves are typically generated using water. When pumping viscous fluids, engineers must apply correction factors (such as those from the Hydraulic Institute) based on the fluid's viscosity in cSt to adjust head, capacity, and efficiency.
Instrumentation: Many flowmeters, particularly turbine and positive displacement meters, are viscosity-sensitive. Calibration limits are often defined in cSt, and operating outside these tolerances can lead to significant measurement drift.

Critical Pitfalls: Engineers must distinguish between kinematic viscosity (cSt) and dynamic viscosity (cP). While they are related by density, using them interchangeably in equations like the Navier-Stokes or Hagen-Poiseuille will result in catastrophic design errors. Furthermore, viscosity is highly temperature-dependent. A common mistake is performing a conversion at ambient temperature for a process operating at high heat; always specify the reference temperature (e.g., $40^\circ\text{C}$ or $100^\circ\text{C}$ per ASTM D445) when documenting these values.

Stokes to Centistokes Conversion Reference Table

Stokes (St)	Centistokes (cSt)
0.1	10
0.5	50
1.0	100
2.0	200
5.0	500
10.0	1000
20.0	2000
50.0	5000
100.0	10000
500.0	50000
1000.0	100000

To convert a kinematic viscosity value from Stokes (St) to Centistokes (cSt), multiply the value by the precision factor of $100.00000000000001$. For a fluid with a measured viscosity of $10\text{ St}$, the calculation is as follows:

\$\$ \nu_{\text{cSt}} = 10\text{ St} \times 100.00000000000001 = 1000.0000000000001\text{ cSt} \$\$

This result ensures that the high-precision requirements of computational fluid dynamics (CFD) modeling are met, maintaining significant digits across complex iterative simulations.

The SI unit $m^2/s$ is inconveniently large for most practical applications. For example, the viscosity of water would be $0.000001\text{ m}^2/s$. Using Centistokes allows engineers to work with more manageable whole numbers (e.g., $1\text{ cSt}$ for water) and aligns with the graduation of most industrial viscometers and ASTM standards.

While the mathematical conversion factor between St and cSt remains constant regardless of pressure, the physical viscosity of the fluid itself changes. In high-pressure hydraulic systems (above 100 bar), the fluid density and molecular spacing change, typically increasing the viscosity. Engineers must ensure the input value in Stokes is corrected for operating pressure before converting to Centistokes for system modeling.

"On fait la science avec des faits, comme on fait une maison avec des pierres ; mais une accumulation de faits n'est pas plus une science qu'un tas de pierres n'est une maison."
"Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house."
— Henri Poincaré (French Mathematician, Theoretical Physicist & Mining Engineer)